Spark plug gap adjuster



Nov. 13, 1945.

J. C. (:QOMBS SPARK PLUG GAP ADJUSTER 2 Sheets-Sheet 1 Filed July 1, 1944 t h E INVENTOR. J. C. CO OM B S Nov. 13, 1945. J co s 2,388,953

SPARK PLUG GAP ADJUSTER Filed July 1. 1944 2 Shegts-Sheet 2 INVENTOR. J. C. COO/7B5 HTTOR VF) Patented Nov. 13, 1945 UNITED STATES TENT OFF] Claims.

This invention. relates to a spark plug gap adjuster.

Thegeneral object of the invention is to provide a spark plug gap adjuster by means of which the spark gap may be accurately adjusted. to the correct width.

A- more specific object of my invention is to provide a spark plug gap adjuster including novel means for effecting the adjustment.

A further object of the invention is to provide a spark plug gap adjuster in'cluding'a novel support for the spark plug..

An additional object of the invention is to provide a spark-plug gap adjuster including a novel head member.

A further object of the invention is. toprovide a spark plug gap adjuster includinga novel indexing device.

Other objects-and the advantages of my invention will be apparent from the following description taken in connection with the accompanying drawings, wherein: V

Fig; l is a side elevation partly in section. showing a spark plug gap adjuster embodying the features of my invention;

Fig. 2 isa topplan'view of the apparatus;

Fig. 3 is a section taken on line 3.-3, Fig.2;

Fig. 4 is an enlarged central sectional view showing the head and associated parts;

Fig. 5 isa fragmentary top plan view looking in the direction of the arrows 5-5; Fig. 6;

Fig. 6 is a fragmentary sectional view similar to Fig. 4 showing the position of the parts after the adjusting operation is completed, and

Fig. 7 is a side elevation of. a gauging member.

Referring to the drawings by reference characters, I have shown. my invention as embodied in a spark plug gap adjuster which is indicated generally at H]. My improved adjuster is particus larly adapted for adjusting the spark. gapsv of spark plugs of the type used: on airplane engines although it isnot limited to. this particular use.

- recess M to hold. the transverse member in place.

The transverse member I!: is provided with bores I8 which receive cylindrical rods or ways |-9 which are parallel to each other and are threadedly connected at their outer ends to a second transverse way supporting member 2| which is parallel to and spaced from the member IT.

The ways I9, at each end, are provided with shoulders 22 which engage the adjacent faces of the transverse members I! and 2|. Theends of the ways l9 adjacent to the transverse member H: are provided with peripheral grooves 23 which receive the slotted portions 24 of a retainer member 25 which is apertured as at 26 to receive the stem I6 previously mentioned. The retainer memberincludes a finger engaging portion 21.

The construction is such that when the retainer member 25 is rocked about its axis the slots 24 move away from the ways I9 thus permitting the latter to be removed from the transverse member l1, thus permitting substitution or repair.

The ways l9 support a head member 28 which has bores 29 receiving the ways and permitting the head member to slide back and forth on the ways.

The head member 28 includes a generally cylindrical' body portion 30 which is disposed between the ways and includes an upper cylindrical portion 3| and an intermediate cylindrical bore 32 which is-larger in diameter than the bore 3| and a lower threaded bore 33 which is larger than the bore 32. The bore 32 receives a removable rotatable bushing 34' which is internally threaded as at 35;

The bushing 34 is held in place by a threaded annular collar 36 which engages the threads of the bore 33. The body 30 is provided with a pair of bores 31' and 31 which are aligned and which intersect the'bores 31' and 32. The bushing 34 is rabbetecl as at 38 with the bottom of the rabbet substantially flush withv the bottom of the bores 3'| and 37'.

The bore 3! receives an anvil member 39 which has an end portion 40 in a bore 4| in the transversemember 2|. The transverse member 2| is provided with an aperture 42 which has a spring 5 3 and set screw l3 therein normally urging a ball 44 into a recess 45 in the. portion 40. This construction serves to removably hold the anvil member 39' in place.

Opposite to and aligned with the anvil member 39 I provide a second anvil member which is slidable in the bore 3'5. The anvil member 41 extends from the head body 3|! and is slidable in a bore 48 in the transverse member IT.

The anvil member 4? terminates in an end 49 which is disposed in the slot l5. The arms 50 defining: the slot Hi arev provided with aligned apertures 5| which receive a shaft 52. shaft 52 supports an arm 53 which has a spacing boss 54. on each side thereof. The arm 53 includes a cam face 55 which engages the end 49 of the anvil member 41 and the construction is such that when the arm 53 is rocked downwardly from the position shown in Fig. 1 the movable anvil member 41 will b moved towards the fixed anvil member 39.

As stated above, my apparatus is particularly adapted for adjusting the spark gaps of a spark plug such as indicated at 56. In use the threaded portion of the spark plug is screwed into the threads 35 of the bushing 34 with the usual washer 5! in place upon the spark plug. The bushing 34 is of such thickness that the upper end 59 of the spark plug will be substantially level with the adjacent end 60 of the bushing, so that the parts assume the position shown in Fig. 4, wherein the spark plug is shown as including opposed pairs of electrodes 8| arranged about a central electrode 63.

The gauging member shown in Fig. 7 includes a handle ,64 having spaced blades 65 of the correct thickness inserted in slots therein and held in place by screws 66.

The anvils 39 and 4'! have upper end portions Bl which merge by curved portions 68 into fiat portions 69 which latter terminate at the shoul der 10. The portions 69 move over the adjacent ends 69 of the bushing 34;as shown in Figs. 4 and 6.

In order to index the bushing 34 to correctly position the spark plug during the adjusting operation, I provide the upper surface of the bushing 34 with a plurality of holes 19 which are alignable with a pin H which is slidable in a hole in the head 30. The upper end of the pin H passes'through and is secured to a spring arm 12 which is held in place by a screw 13.

In using my apparatus the bushing is rotated until the lower end of the pin H drops into one of the holes Hi. Thereafter the spark plug is threaded into place and when fully seated assumes the position shown in Fig. 5.

The blades 65 of the gauging member are then inserted between the central electrode 63 and the adjacent pair of electrodes 6|. The arm 53 is then rocked to advance the anvil member 41 so thatthe end 6'! thereof engages the adjacent terminal 6! and pushes the entire spark plug and head 30 forwardly until the other terminal Bl engages the end 61 of the anvil 39, whereupon the act of adjusting the spark gap begins. Further movement of the arm 53 moves the parts to the position shown in Fig. 6, wherein the an vils have forced the movable electrodes towards each other and against the blades 65 which latter are forced against the central electrode 63. The thickness of the blades 65 determines the width of the spark gap.

After the adjustment is made the arm 53 is swung upwardly and the arm 12 is raised to lift the pin H. The bushing 34 is rotated 90 and the pin H is released. The arm 53 is again operated and the other pairs of electrodes is thereby adjusted. The spark plug is then removed.

By use of the removable bushing and by using different ways and difierent head members as well as difierent anvils I am able to use my apparatus with many difterent types of spark plugs.

From the foregoing description it will be apparent that I have invented a novel spark plug gap adjusting device which is simple in construc- The tion and which is highly efiicient for its intended purpose.

Having thus described my invention, I claim:

1. In a spark plug gap adjusting device, a body portion, a head member, means to movably support the head member on said body portion, said head member having a hole therethrough, a bushing, means to rotatably support the bushing in the hole, said bushing having a threaded hole, said bushing threaded hole being adapted to receive the threads on a spark plug and the parts being so arranged that the electrodes on the spark "plug will project into the body portion hole, said head member having opposed, transverse, aligned bores, said transverse bores intersecting said hole, an anvil member mounted in each of said transverse bores, one of said anvil members being fixed relative to the body portion, the other anvil member slidably extending through the body and having an end portion remote from the head, and means to move the other anvil member towards the first anvil member.

2. In a spark plug adjusting device, a body portion, a pair of ways, means to support said ways on said body portion, a head member slidable on said ways, said head member having a cylindrical bore, a second bore above and smaller than the first bore, a bushing in said first bore, means to rotatably support the bushing, said bushing-having a threaded hole, said bushing threaded hole being adapted to receive the threads on a spark plug and the parts being arranged so that the electrodes on the spark plug will extend into the second cylindrical bore, said head member having opposed, transverse, aligned, bores, said transverse bores intersecting the second body portion bore, an anvil member mounted in each of said transverse bores, one of said anvil members being fixed in relation to said ways, the other anvil member slidably extending through the body and having an end portion remote from the head, an operating arm movable on said body, means whereby said operating arm moves the other anvil member towards the first anvil member, and means to index the bushing.

3. In a spark plug adjusting device, a body portion, a pair of ways, means to support said ways on said body portion, a head member slidable on said ways, said head member having a cylindrical bore, a second bore above and smaller than the first bore, a bushing in said first'bore, means to rotatably support the bushing, said bushing having a threaded hole, said bushing threaded hole being adapted to receive the threads on a spark plug and the parts being arranged so that the electrodes on the spark plug will extend into the second cylindrical bore, said head member having opposed, transverse, aligned, cylindrical bores, an anvil member mounted in each of said transverse bores, one of said anvil members being fixed in relation to said ways, the other anvil member slidably extending through the body and.

havingan end portion remote from the head, an operating arm movable on said body, means whereby said operating arm moves the other anvil member towards the first anvil member, and means to index the bushing.

4. In a spark plug adjusting device, a body portion, a pair of ways, means to releasably support said ways on said body portion, a head slidable on said ways, said head member having a hole in the lower side thereof and having a cylindrical bore above and coaxial with the hole, said bore being larger than the hole, a second bore above and smaller than the first bore, a

cylindrical bushing in said first bore, means to rotatably support the bushing, said bushing having a threaded hole, said bushing threaded hole being adapted to receive the threads on a spark plug and the parts being arranged so that the electrodes on the spark plug will extend into the second cylindrical bore, said head member having opposed, transverse, aligned, cylindrical bores, an anvil member mounted in each of said transverse bores, one of said anvil members being fixed in relation to said ways, the other anvil member extending through the body and having an end portion remote from the head, an operating arm pivoted on said body, means whereby said operating arm moves the other anvil member towards the first anvil member, each of said anvil members including a rod having a fiat face which is directed downwardly, said flat faces being adapted to pass over the rim of a spark plug, and means to index the bushing.

5. In a spark plug adjusting device, a base, a body portion on said base, a pair of ways on said body portion, a head member slidable on said ways, said head member having a threaded hole in the lower side thereof, and having a cylindrical bore above and coaxial with the hole, said bore being larger than the hole, a second bore above and smaller than the first bore, a bushing in said first bore, a threaded collar in said hole for rotatably supporting said bushing, said bushing having a threaded hole extending therethrough, said bushing threaded hole being adapted to receive the threads on a spark plug and the parts being arranged so that the electrodes on the spark plug will extend into the second cylindrical bore, said head member having opposed, transverse, aligned cylindrical bores, an anvil member mounted in each of said transverse bores, one of said anvil members being fixed in relation to said ways, the other anvil member extending through the body and having an end portion remote from the head, an operating arm pivoted on said body, said operating arm having an eccentric head forming a cam, said cam being disposed to engage said end portion of said other anvil member to move the other anvil member towards the first anvil member, each of said anvil members including a cylindrical rod having the lower end portion thereof cut away to provide a flat face which is directed downwardly, said flat faces being adapted to pass over the rim of a spark plug, and means to index said bushing.

JOSEPH C. COOMBS. 

